Biomarker is the change associated with the disease. Blood is relatively stable because of the homeostatic mechanisms of the body. However, urine accumulates changes of the body, which makes it a better early biomarker source. Liver fibrosis is a reversible pathological condition, whereas cirrhosis, the end-stage of liver fibrosis, is irreversible. Consequently, noninvasive early biomarkers for fibrosis are desperately needed. In this study, differential urinary proteins were identified in the thioacetamide liver fibrosis rat model using tandem mass tagging and two-dimensional liquid chromatography tandem mass spectrometry. A total of 766 urinary proteins were identified, 143 and 118 of which were significantly changed in the TAA 1-week and 3-week groups, respectively. Multiple reaction monitoring (MRM)-targeted proteomics was used to further validate the abundant differentially expressed proteins. A total of 40 urinary proteins were statistically significant, 15 of which had been previously reported as biomarkers of liver fibrosis, cirrhosis or other related diseases and 10 of which had been reported to be associated with the pathology and mechanism of liver fibrosis. These differential proteins were detected in urine before the alanine aminotransferase and aspartate transaminase changes in the serum and before fibrosis was observed upon hematoxylin and eosin (HE) and Masson's staining.
Patients with primary and metastatic brain cancer have an extremely poor prognosis, mostly due to the late diagnosis of disease. Urine, which lacks homeostatic mechanisms, is an ideal biomarker source that accumulates early and highly sensitive changes to provides information about the early stage of disease. A rat model mimicking the local tumor growth process in the brain was established with intracerebral Walker 256 (W256) cell injection. Urine samples were collected on days 3, 5 and 8 after injection and then analyzed by LC-MS/MS. In the intracerebral W256 model, no obvious clinical manifestations changes or abnormal MRI signals were found on days 3 and 5; at these time points, nine proteins were changed significantly in the urine of all 8 tumor rats. On day 8, when tumors were detected by MRI, twenty-five differential proteins were identified, including 10 proteins that have been reported to be closely related to tumor metastasis or brain tumors. The differential urinary proteomes were compared with those from the subcutaneous W256 model and the intracerebral C6 model. Few differential proteins overlapped. Specific differential protein patterns were observed among the three models, indicating that the urinary proteome can reflect the difference when tumor cells with different growth characteristics are inoculated into the brain and when identical tumor cells are inoculated into different areas, specifically, the subcutis and the brain.
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